1. Field of the Invention
The present invention relates to a piston for an internal combustion engine, having a lower piston part and an upper piston part that are connected with one another by friction welding and form an outer circumferential cooling channel. The upper piston part has a circumferential ring belt provided with ring grooves, the inner wall of which delimits the circumferential outer cooling channel.
2. The Prior Art
A piston of this type is described in U.S. Pat. No. 6,557,514 B1. The outer circumferential friction-weld seam between the upper piston part and the lower piston part is disposed in the region of the ring belt, between two ring grooves. In this connection, however, there is the risk that tension is built up during friction welding, which impairs the stability of the piston.